It’s common, wide spread around the globe, and yet I have only noticed it in recent weeks. I photograph everything that moves and much that doesn’t in these bays, but this particular organism has evaded me. So, has it just arrived here on Norfolk Island? No. There is a record of it back in 1973 in the biocache of the Atlas of Living Australia.[i] It is simply a spongey blob that goes unnoticed, merging into its environment, hiding in plain sight.

Once noticed and photographed, I felt duty bound to investigate further! My first thoughts were that it was a sea sponge – a type of invertebrate, an animal, that is covered in pores (from the phylum Porifera: Latin words ‘porus’ (pore) and ‘ferre’ (bear), meaning ‘pore-bearer’.[ii]

But no. It isn’t a sponge but instead is an algae, Hydroclathrus clathratus, commonly known as a sponge seaweed.

They have a curious form – blob-like, but with large perforations in a jelly-ish mass that forms an open network. They grow to about 25 cm in size and are light tan through to a brown colour.[iii] They can be eaten, usually in salads, or used as a spice, or in animal feed.[iv]

But here’s the really interesting thing, this edible seaweed has been shown to:

• ‘significantly affect[ed] the growth of human acute promyelocytic leukemia cells … human breast carcinoma … and human hepatocellular carcinoma cancer cell lines’[v]

• prolong the life span of mice that had tumours by between 30 and 40%[vi]

• contain a chemical that is a strong inhibitor of herpes simplex virus[vii]

• inhibit the corrosion of mild (as in low carbon) steel[viii]

• protect lung tissue in mice from the damage produced by ingesting copper sulphate (which are found in some pesticide products, for example).[ix]

That’s quite an arsenal of possible uses!

For me, it just goes to illustrate what amazing finds are waiting to be discovered beneath the waves!

References

 [i] https://bie.ala.org.au//species/NZOR-6-4599

[ii] https://www.thoughtco.com/sponges-profile-2291833

[iii] http://hbs.bishopmuseum.org/botany/algaekey/html/hydclat.html

[iv] http://www.wildsingapore.com/wildfacts/plants/seaweed/phaeophyta/perforated.htm

[v] https://www.degruyter.com/document/doi/10.1515/BOT.2010.029/html

[vi] Ibid

[vii] https://link.springer.com/article/10.1007/s11274-010-0348-0

[viii] https://link.springer.com/article/10.1007/s11164-012-0883-4

[ix] https://bjbas.springeropen.com/articles/10.1186/s43088-020-00045-z